Rod mills, such as those in which copper rod is formed from molten copper, typically have several manufacturing operations at different stations through which the copper rod is passed for processing. Some mills are designed in a manner requiring the rod be moved along a nonlinear path between stations in order to avoid an obstruction or to change direction or elevation. In such cases it is a common practice to provide a guide tube through which the rod is passed that effects a change in its direction of movement as by being routed over a roller mounted within the tube. Since the rod is moving at a rapid rate of speed, such as in excess of 200 kilometers per hour, it sometimes occurs that a "cobble" or entanglement of the rod is formed adjacent the entry end of the guide tube. These cobbles are most frequently created during start-up when a rough edge of the rod strikes a part of the rod processing equipment causing its movement to be impeded. If a cobble is formed adjacent the entry end of the guide tube it will rapidly back up and become entangled with the rod forming rolls or other processing apparatus located immediately upstream from the tube. To prevent this from happening the guide tubes have been designed to dissasemble whenever a cobble is formed about or within it. This feature has been provided by having the guide tube formed of two sections releasably fastened together so that when pressure exerted by the rod against the guide roller or the interior walls of the tube exceeds a certain amount one section is released from or "pops" off the other providing space above the tube to accommodate the cobble as it is formed before the line has been shut down.
More specifically, rod mill guide tubes have typically been in the shape of a hollow cylinder formed with a semi-cylindrical cover section fastened to a semi-cylindrical base section. The two sections have been fastened together by means of tie wires or spring clips secured to one section while overlaying the other. However, unless the two sections are and remain precisely aligned with one another the seam at their interfacing surfaces will present an edge to the tube interior. Furthermore, as a rod wobbles or whips about during its passage through the tube is applies varying degrees of pressure against the guide tube roller causing the two tube sections to move somewhat relative to each other and become misaligned. When this occurs any section edge or seam will become more exposed which can scratch or mar the rod. Accordingly, it is to the task of eliminating the just-described adverse characteristics of present day rod mill guide tubes that the invention is primarily directed.